>5. Has this ever happened to anyone else? I racked my Clara Bell batch
>from the primary to the secondary day before yesterday. The head had
>just fallen after a healthy, vigorous initial fermentation. However, I
>noticed the next day that fermentation had completely stopped. I've
>experienced this before where racking seems to shock the yeast
>temporarily (up to a few days), and then fermentation resumes. I'm
>always careful to let the wort cascade down the side of the glass

Don't do that. Running the wort down the side in a thin film causes
air to dissolve in the wort. Run the hose or another racking tube all
the way down and fill the new container from the bottom up instead.

>carboy to minimize oxygentation, and I always make sure to syphon a
>big slug of yeast with the wort in an attempt to assure continuous

This is not needed. There are many many millions of yeast cells
suspended in the actively fermenting wort you are racking.

>fermentation. However, about half the time I notice that
>fermentation comes to a complete halt for up to 3 or 4 days, after
>which it slowly resumes. Any ideas?

I'm going to go out on a limb and suggest that the infusion of new
oxygen caused by improper racking might have triggered another
respiration phase in the yeast, causing the pause you observed.